Conventionally, in forming the roof and external walls of a building with metallic panels, the panels are joined to one another through seams or other male-and-female fitting structures formed on the panels, so as to form the roof and the external wall. Also, for constructing the roof and the external walls of plastic material, it is a common measure to superimpose the end portions of adjacent corrugated plastic plates and fix them to each other by means of nails or the like.
However, the roofs and external walls constructed by the above stated methods have various drawbacks or shortcomings as set forth below.
Namely, concerning the roofing material, in the case of a flat roof, troublesome work of material preparation and bending of a major part of the seam at the factory, as well as sheet metal work, i.e., hitting and flattening of the seams, after the engagement of the seams at the site, are indispensable, which inconveniently reduces the working efficiency. In addition, the packing and transportation of the plate materials are rendered toublesome and difficult due to the presence of seams on these plates. Furthermore, the roof having the described structure often suffers from corrosion of sheathing board and so on, due to invasion by rain water caused by capillary action. In addition, this type of structure requires accessories or additional parts such as clips, which inconveniently reduce the working efficiency and increase the cost of the building. At the same time, the roof constructed with architectural material of this kind can have only a flat face of poor designability and three-dimensional appearance.
In the case of external walls constructed with this kind of material, the work is rendered quite inefficient, partly because the plane to be worked is always vertical and partly because the materials are used for different areas of the wall. The resulting wall has also a poor three-dimensional appearance.